Solid state radiation imaging arrays typically comprise a photosensor array coupled to a scintillator. The radiation to be detected (e.g., x-rays or the like) penetrates the scintillator and is absorbed by the scintillator material in an event that results in the release of optical photons. The photosensor array coupled to the scintillator is used to detect the optical photons, providing a spatial location (x,y) in the array that corresponds with the point in the scintillator at which the incident radiation was absorbed. Readout of the photosensor array allows electrical signals to be generated that correspond to the pattern of absorbed radiation. The data embodied in such electrical signals can be presented in a visual display or otherwise processed to allow analysis of the radiation pattern.
Good spatial resolution in an imager necessitates that the optical photons generated in an absorption event be detected by a photosensor in the immediate vicinity of the absorption event so that the electrical signal representing the absorbed radiation originates from a sensor in the array near the absorption event. Photons generated in the absorption event, however, are emitted in all directions and will readily travel through the scintillator material, which typically is substantially optically transparent. The multi-directional emission of optical photons from an absorption event results in approximately half of the photons moving in a direction away from the photosensor array; these photons are not only not directly detected by the photosensor array but also can be reflected off the surface of the scintillator opposite the photosensor array along paths that cause them to strike the photosensor array at a point away from the spatial location (x,y) of the absorption event, thus degrading the spatial resolution and image quality provided by the imager.
Reduction of optical crosstalk, that is, optical photons that are incident on the photosensor array at a point distant from the spatial location (x,y) of the absorption event, is desirable to improve spatial resolution and image quality.